POLICE and MI5 are grappling with an “exceptionally high” number of Islamist terror plots every year ranging from lone-wolf attacks to complex conspiracies, it was revealed yesterday.

Officers have arrested 218 suspects this year and specialist teams are seizing around 1,000 chilling videos a week of beheadings and other atrocities.

The figures were announced by Britain’s top anti-terror police chief Assistant Commissioner Mark Rowley as he gave an insight into the fight against Islamic State militants.

He would not spell out how many attacks have been foiled but one estimate is 30 every year.

He said police have charged 16 people returning to Briton over alleged terrorist activity in Syria.

He said police are “running exceptionally high numbers of counter-terrorism investigations the likes of which we have not seen for several years” and added: “Against an increasing operational tempo, we are disrupting several attack plots a year.

“These plots are of varied sophistication, from individuals planning to carry out spontaneous yet deadly attacks to more complex conspiracies.”

In the statement from Scotland Yard, Mr Rowley said the volume, range and pace of counter-terrorism activity has undergone a “step-change”.

On occasions, detectives have had to move in quickly to ensure a suspected plot is foiled.

Mr Rowley said: “Public safety is our number one priority and we will always focus our activity against those posing the greatest and most imminent threat.”

The Counter Terrorism Internet Referral Unit, which plays a key role in the battle against Islamist extremism, has seized 51,000 pieces of damaging material in the past four years – 80 per cent relating to Iraq and Syria.

Mr Rowley said there was a “growing problem of young, impressionable individuals being radicalised online”.

A total of 66 people have been reported missing “presumed in Syria”. But some experts fear the real number is as high as 2,000.